Biocompatibility and Biodegradation of Deproteinized Human Demineralized Tooth Matrix (dpDTM) in Rabbit Model

Abstract

Background and Objectives: Tooth is a composite structure consisting of inorganic and organic components which are very similar to those of alveolar bone. The autologous tooth matrix has been successfully developed and has been used clinically as bone substitution in various bone defect model. However, the major drawback of the autologous tooth matrix is the limited availability of the graft. Therefore, deproteinized human demineralized tooth matrix (dpDTM) was developed into allograft materials to overcome those limitations. The aims of this study were to assess and compare the biocompatibility and biodegradation of dpDTM and anorganic bovine bone (ABB) by intramuscular implantation at 1, 2, 4, 8, 12 weeks Materials and Methods: dpDTM was prepared by using 0.5M HCl for demineralization. Deproteinization was performed by using dual chemical-thermal treatment (NaOH IN, 300°C). 5%wt/v Polyvinyl alcohol (PVA) was used to fabricate scaffold using hydrogel solution as binding materials and the scaffolds were prepared by freeze-thawing method. The dpDTM, ABB and PVA scaffolds (n=6/group/time point) were implanted into paralumbar muscle of the 15 adult New Zealand White rabbits. The biocompatibility analysis was performed by clinical and histological methods. The biodegradation analysis was achieved by histological images and Micro computed tomography (Micro-CT). All the assessments were performed after healing period of 1, 2, 4, 8 and 12 weeks. Results: All rabbits recovered uneventfully without weight loss. Clinical observation revealed the absence of infection and inflammation at all time point. Histological data of dpDTM and ABB bone indicated the moderate to intense inflammatory response at 1-2 weeks and decreased with time to moderate grade inflammatory response at 8-12 weeks. The mean inflammatory cells count was not significant different between two groups at all time point. According to the biodegradation, the relative bone volume/total volume (BV/TV) in dpDTM scaffolds was greater than that in ABB scaffolds at all time point. The percentage of reduction in dpDTM and ABB were 1.663% and 1.897% respectively. Conclusions: In terms of biocompatibility, dpDTM and ABB demonstrated good biocompatibility with moderate degree of inflammatory cells infiltration at 12 weeks. Both materials had potential to degrade with time with a slow degradability rate. Suggesting that dpDTM was favorable for reconstructive bone graft substitution due to its good biocompatibility together with the slow degradation profiles. However, clinically relevant implantation studies should be concerned before human used of this tooth graft material.